Gearing an ERBE for racing on 4s

[suicideneil]

Whats the diameter of those tires?

Educated guess:

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.8333333333333332
Other Ratio: 1
Spur Tooth Count: 68
Pinion Tooth Count: 24
Total Voltage: 14.8
Motor KV: 2250
Tire Diameter (inches): 5.8
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 2.83 : 1
Total Ratio: 14.78419 : 1
Tire Circumference (inches): 18.22 inches (462.82 mm)
Rollout: 1.23:1
Total Motor Speed: 33300 RPM
Vehicle Speed: 38.87 mph (62.43 km/h)
Effective KV Value: 2250
KT constant: 0.6 oz-in/A

http://www.scriptasylum.com/rc_speed/_top_speed.html

68/24 should be good for just shy of 40mph, perfect for racing. Just make sure you have good lipos really.

I plan to use TP 5000mAh 40C lipos, so lipo quality should be fine. That's the calculator I used, but was struggling a bit with. Tires are 5.6 I believe.